The grain will form a filter, where the larger particles will settle in lower and the finer particles will settle up higher. After you've sucked a bit of the wort through the grain bed by draining it into a pan (or whatever) the grain will start to form the filter. The first bit of wort will be cloudy because the grain hasn't had a chance to set up the filter and the wort close to the outlet will have lots of particulate in it.
However, once the grain bed is formed, you can gently pour the collected wort back on top of the grain bed and let it filter that stuff back out. I use a tupperware lid to careful pour my collectings onto, so it will not disturb the grain bed. Tin foil would work good, but I've not tried that yet.
Now that I've got a pump I can recirculate, but I haven't tried that yet.